Evaluación de Tres Programas de Vacunación Contra Laringotraqueitis Infecciosa Aviar Usando Dos Vacunas Vectorizadas Comerciales en Pollos de Engorde

The aim of this study was to evaluate the protection of three immunization programmes against infectious laryngotracheitis (ILT) in broilers using two recombinant commercial vaccines. A total of 288 1-day-old Ross-308-line male birds were distributed in four experimental groups of 72 animals with three replicates of 24 birds per group. Group A was subcutaneously vaccinated at 1 day of age with a commercial recombinant fowlpox virus (FPV)-vectored vaccine expressing ILT virus (ILTV) glycoprotein B gene; Group B was vaccinated at day 14 of age with an inactivated vaccine by subcutaneous route and with the vaccine of Group A but applied via wing-web puncture; Group C was subcutaneously vaccinated at 1 day of age with HVT recombinant commercial vaccine expressing genes encoding for ILTV glycoproteins I and D; and Group D remained unvaccinated. All birds were challenged with ILTV pathogenic strain with 107 DIE50 at 35 days of age. Unvaccinated chicks showed higher degree of respiratory signs on day 6 post challenge than the vaccinated ones (p<0.05). Microscopic lesions varied between groups, but group C presented a faster recovery (p<0.05). Production parameters (body weight, feed conversion index, and European productive efficiency index) showed no significant difference between groups. The best protection against ILT was obtained in birds vaccinated with the HVT recombinant vaccine; however, no difference in productive performance was found between treatments.El objetivo del estudio fue evaluar la protección conferida por tres programas de vacunación contra laringotraqueitis infecciosa (LTI) en pollos de engorde usando dos vacunas comerciales recombinantes (vectorizadas). Se utilizaron 288 pollos machos de la línea Ross 308 de 1 día de edad, distribuidos en cuatro grupos de 72 con tres repeticiones de 24 aves por grupo. El grupo A fue vacunado al 1er día de edad por vía subcutánea con la vacuna recombinante comercial del virus de viruela aviar que expresa el gen de la glicoproteína B del virus de laringotraqueítis infecciosa aviar (VLTI); el grupo B fue vacunado el día 14 con una vacuna inactivada por vía subcutánea y con la vacuna del grupo A aplicada por punción alar; el grupo C fue vacunado el día 1 de edad por vía subcutánea con una vacuna recombinante comercial de herpesvirus de pavo (HVT) asociado a células que expresa los genes de las glicoproteínas I y D del VLTI; y el grupo D no fue vacunado. Todas las aves fueron desafiadas con una cepa del VLTI con un título de 107 DIE50 el día 35 de edad. Las aves control presentaron mayor severidad de signos respiratorios en el día 6 posdesafío que las vacunadas (p<0.05). Las lesiones histopatológicas variaron entre grupos, siendo el grupo C el que tuvo la más rápida recuperación (p<0.05). Los parámetros productivos (peso corporal, índice de conversión alimenticia e índice de eficiencia productivo europeo) no mostraron diferencias estadísticas entre grupos. La mejor protección contra LTI se obtuvo con la vacuna recombinante HVT, no habiendo diferencia estadística en la respuesta productiva entre los cuatro tratamientos

Assessment of the interface shear strength of metal-polymer system based on the single filament fragmentation test method

Among the different test methods to characterize the fibre/matrix interfacial shear strength, the fragmentation test is one of the most simple in terms of experimental setup and the amount of data that can be extracted from one single test. In this work, the fragmentation test method was implemented to assess the interface shear strength obtained for a single steel filament embedded in an unsaturated polyester resin.. The fragment lengths were discriminated and processed using the Kolmogorov-Smirnov and Chi-square fitting test methods showing that the fragment lengths correspond to the extreme statistical distributions. In addition, a very high shear strength (67MPa) of the steel/polyester interface was estimated using the Kelly and Tyson criteria considering the critical fragment length

Assessment of Ichu fibers as non-expensive thermal insulation system for the Andean regions

In the Andean regions, low temperatures (5 to −25 °C) combined with the wind effect give the sensation of extreme cold. Besides, in the rural areas, dwelling structures are very rudimentary, being based on adobe walls and galvanized steel corrugated roofs. The combination of weather issues and construction without thermal insulation considerations put people in extreme living conditions. Using local and cheap natural fibers as thermal insulation is a great alternative especially to upgrade/refurbish rudimentary constructions. In areas above 3000 m over sea level, natural fibers are vast and cheap (∼0.15 USD/kg), especially fibers named “Ichu”. In this study thermal properties of natural fibers were characterized according to the ASTM C177. Results show that the thermal conductivity varies from 0.047 to 0.113 W/m K, for mats with unidirectional oriented fibers, being fine Ichu which have the lowest values. For the fine Ichu fiber to be competitive in terms of cost per unit thermal resistance, fiber mat density were reduced, arranging the fibers randomly; results show a significant reduction in density, without increasing significantly the thermal conductivity. According to these results Ichu fibers have exceptional thermal insulation properties. Moreover, this is the first conducted study on the thermal performance of this natural Andeans fiber

Assessment of Ichu Fibers Extraction and Their Use as Reinforcement in Composite Materials

This paper describes the research conducted to develop an optimal methodology to extract useful fibers from the “Ichu” grasses which can be used as reinforcement of polyester resin. Laminates were manufactured and their flexural properties were characterized as well as the optimal fiber properties. Results show that for this kind of materials, the mechanical and retting treatments are insufficient to remove lignin from the raw material state; on the other hand, alkali treatments are considerably effective. Laminates transverse strength shows an improvement (up to 30 MPa) when the alkali treatment time increases. Longitudinal strength and modulus present values around ~144 MPa and ~8.8 GPa respectively with fiber volume fraction around 0.38